As device geometries continue to shrink, one of the challenges facing the semiconductor industry is the deposition of thin, continuous films for use as copper diffusion barriers and as seeds for electroplating. The inability to grow thin, continuous metal films by chemical vapor deposition or pulsed layer deposition is often due to the inability of the metal films to nucleate on the dielectric surface
“Nucleation” refers to the initial formation of metal nuclei on a substrate such as a dielectric layer. Often the process conditions present a kinetic barrier to formation of such nuclei. In such cases, there may be a delay in deposition between the time when the substrate is exposed to metal precursor and the time when the metal actually begins to form on the surface. The problem may also be manifested by higher substrate temperatures required to initiate nucleation during the process.
Additionally, current methods for the deposition of ruthenium form rough, non-uniform films, often with incomplete coverage.
What is needed, therefore, is a process for allowing a reduction in nucleation delay and improvement of morphology of ruthenium films.